Automatic Transmission/Transaxle: Description and Operation

Fig. 1 AR-4 Automatic Transaxle:

Fig. 2 Transmission Control Unit (TCU) & Sensor Harness Locations:

The AR-4 automatic transaxle, Fig. 1, has four forward speeds and one reverse and is used on all Eagle Premier models with 2.5L/4-150 engines. Fourth gear is an overdrive range providing an 0.68:1 gear ratio. The transmission and differential are not integral and require different lubricants.
The transaxle consists of a three element torque converter, clutch and brake mechanisms, front mounted oil pump, external oil cooler and an electronically controlled valve body.
The transmission control unit (TCU), Fig. 2, controls transaxle shifting. The TCU receives and analyzes input data from the temperature sensor, throttle position sensor, vehicle and engine speed sensors, line pressure sensor and a multi-function switch. Using this data, the TCU transmits shift commands to the valve body solenoids.